Investigations across numerous disciplines have identified respondent culture as a potential source of systematic measurement variability in survey research. This measurement bias can lead to a number of problems including errors in hypothesis testing, flawed population forecasts and policy planning and implementation, and misguided research on disparities. This is a particular problem in the measurement of trust in health care because minority populations in the United States have had and continue to have dramatically different experiences of health care than non-Hispanic whites;yet most instruments to measure trust in health care have been developed and validated for use with predominantly non-Hispanic white populations. The purpose of the proposed research is to improve the cross-cultural measurement of trust in physicians and health care institutions across the three largest racial/ethnic groups in the United States: African Americans, Mexican Hispanics, and non-Hispanic whites. Our primary objective is to produce instruments to measure trust in health care that are culturally relevant and that provide reliable, comparable measurements across these three different racial/ethnic groups. We propose to meet this objective by using qualitative and quantitative methods to (1) maximize the measurement equivalence of three overlapping, culturally specific measures of institutional trust in health care developed for African Americans and adapted for use with Hispanics and non-Hispanic whites and (2) to adapt current measures of interpersonal trust in physicians to better measure this construct in these three racial/ethnic groups. In addition, we will use these two, improved measures to describe the predictors of trust in health care among African Americans, Mexican Hispanics, and non-Hispanic whites and to explore group differences in levels of health-related trust and how those differences might be explained by between group differences in predictors of health-related trust. PUBLIC HEALTH RELEVANCE: Because trust in health care is an important determinant of health care outcomes, differences in levels of health-related trust across population groups likely contribute to health care disparities. However, researchers'ability to measure such relationships and how trust in health care varies across racial/ethnic groups has been limited by a lack of instruments that can accurately measure this trust cross-culturally. The research proposed here will provide researchers with valid, accurate tools for measuring trust in health care across the three major racial/ethnic groups in the United States and with information about what factors might contribute to differences in trust in health care and therefore disparities.